This invention relates generally to a fluid filter suitable for a broad range of applications and which may be especially advantageously employed in the filtration of corrosive gasses and solvents used by the electronics industry in the manufacture of integrated circuits. It will be apparent, however, that the filter structure of this invention may be used wherever fluid system contamination must be avoided. It is particularly adapted for mounting upstream from solenoid and metering valves where the filter acts efficiently to reduce wear and prevent clogging of orifices and clearances between mating parts so that the protected equipment can function as intended.
The known filter structures of this general type routinely utilize either circumferential or axial sealing for sealing the filter cartridge to the housing. U.S. Pat. No. 3,151,071 to Kasten illustrates a plurality of filter cartridges, each having an extension which is received by an opening in a partition disposed in the interior of the housing. A bead located on the periphery of the extension is subject to circumferential pressure, thereby effecting a seal with the inside diameter of the opening in the partition. While suitable for relatively low pressure applications, if the pressure differential across the filter is greater than the sealing force exerted on the bead, the seal may be broken, thereby permitting unfiltered fluid to bypass the filter element.
Axial sealing is effected in some known filter structures, as illustrated in U.S. Pat. No. 3,240,342 to Callahen, Jr., et al., by utilizing a spring to urge the filter cartridge axially into a sealing engagement with the housing. Generally, however, no other provision is made to prevent the loss of the sealing condition in the event the flow of fluid through the filter is reversed, whereby the force of the reverse flow against the filter cartridge may be greater than the force exerted by the spring. In such an instance, the cartridge may move axially in the housing, breaking the seal and opening a direct communication between the prefiltered and filtered fluid.
Accordingly, it is the principal object of the present invention to provide a fluid filter which is reliable and which will maintain a positive seal in the event the flow of fluid through the filter is reversed.
Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which: